Method of operating an electrolytic chlorine production cell



March 11, 1969 H. H. HOUTZ ETAL 3,432,411

METHOD OF OPERATING AN ELECTROLYTIC CHLORINE PRODUCTION CELL Filed Dec. 8, 1965 Sheet 4 of 2 Arm/Fryers March 11, 1969. H. H. HOUTZ ETAL METHOD OF OPERATING AN ELECTROLYTIC CHLORINE PRODUCTION CELL Sheet 2 of 2 Filed Dec. 8, 1965 4 Z RT mwm m WH IDE 0 MN m m w u M m a n m Q 1 z w u T: 9 5 4 151! m\ m fiw mfi ww m QM. N Q My N w m w QM QN ww MN m\ Q 3 Arrows 5Y5 United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE To decrease the power requirements of a chlorine production cell due to uneven erosion-caused irregularities in the anodes, the anode supporting frame is periodically removed from the cell and placed in a resurfacing machine. Since a number of anodes are suspended from the supporting frame, they can all be resurfaced as a unit to establish coplanar surfaces. The resurfacing machine supports the anode supporting frame in the position that it assumes in the cell.

This invention relates to a method of and apparatus for resurfacing brittle material. More specifically, this invention relates to a method of and apparatus for resurfacing the anode of a cell used in the manufacture of chlorine gas wherein the anode is formed from graphite or similar brittle material.

One of the most widely practiced methods of manufacturing chlorine is by electrolysis. This procedure involves the practice of passing a brine solution between a cathode and an anode in an electrolytic cell and then passing a direct current between the anode and cathode using the brine as an electrolyte. The brine solution can be formed of sodium chloride, potassium chloride, or the like, but is usually sodium chloride. The brine solution is a strong electrolyte and has a high degree of dissocia-.

tion between the sodium ions and chloride ions.

The cathode is usually formed of mercury. The anode, however, is usually formed of graphite and is positioned a predetermined distance directly above the mercury cathode in the cell. When direct current is passed between the cathode and anode using the brine as an electrolyte, the sodium ions will be attracted to the mercury cathode while the chloride ions will be attracted to the graphite anode. When two chloride ions join together, chlorine gas is formed. The chlorine in the gaseous form bubbles up and around the anodes and is collected in a conventional manner.

One of the problems that exists in this type of system is the highly corrosive nature of the chlorine gas. Accordingly, as the chlorine bubbles up and around the outer periphery of the rectangular anodes, the outer portions thereof will tend to erode away. Therefore, in time the lower surface portion of the anode will be cup-shaped making the distance between the anode and cathode relatively longer at the outer edge portion than at the middle of the anode. In order to maintain optimum recovery of the chlorine gas, the power input between the anode and cathode must be increased as the anodes wear away. Of course, the power increase between the anode and cathode greatly increases the recovery cost of the chlorine.

One way to obviate the problem of power increase, is to move the anode closer to the cathode. This will substantially decrease the distance between the outer portion of the bottom surface of the anode and the cathode to provide optimum operating conditions. However, this will also decrease the distance between the anode and cathode at its middle portion. Thus, if the anode is moved too 3,432,41 1 Patented Mar. 1 1, 1969 close to the cathode arcing between the anode and cathode will occur which results in a short circuiting that destroys both the anode and cathode. Accordingly, care must be taken to maintain an optimum distance between the anode and the cathode. When the voltage increases to the predetermined high point, it is required that the anode be completely replaced.

The object of this invention is to provide a method of and apparatus for decreasing the voltage drop between the anode and cathode which results in decreased power consumption.

Another object of this invention is to provide a method of and apparatus for increasing the useful life of a graphite anode in an electrolysis system by resurfacing the lower portion thereof to substantially a horizontal plane which results in decreased power consumption.

Other objects and advantages will become manifestly clear to those skilled in the art when taken in conjunction with the following description and detailed drawings wherein:

FIGURE 1 is a side elevation of the apparatus usable for the present invention with parts broken away to show internal details.

FIGURE 2 is a top view of the apparatus of this invention with parts broken away to show internal details.

FIGURE 3 is a cross sectional view taken on line 3-3 of FIGURE 1.

FIGURE 4 is a detailed cross sectional view illustrating the manner in which the anode is mounted within the apparatus.

Referring to the drawings, the resurfacing machine is generally indicated at 1. The machine .1 is provided with a frame structure 2 consisting of upright and horizontal legs 3 with bracing 4. Intermediate the upright legs 3 is positioned a sectional tank 5 connected to the frame structure by conventional means such as by bolts 6. The upper section 5' of the sectional tank 5 extends around the upper portion of the upright legs 3. It is provided with a lip portion 7 on a lower end thereof and is connected to the legs by bolts 8.

Above the lip portion 7 of upper section 5' is mounted an L-shaped support member 9 connected to the frame by bolts 10. The upper surface of the lateral portion of the L-shaped support 9 provides a supporting surface for the lower run of chain 43. Above the L-shaped member 9 is mounted a U-shaped member 11 supported by the frame by bolts 12. The lower portion of the U- shaped member is provided with a plate member 13 for a purpose to be hereinafter described. The upper portion of the U-shaped member provides a supporting surface for the upper run of chain 43.

The graphite anode 14 is mounted intermediate the supporting members 3 and is provided with a supporting plate 15 having openings 16 extending therethrough at the outer portion thereof. Reinforcing beams 17 are positioned above the support plate 15 to provide rigidity to the support plate 15. Graphite anodes 21 are supported by the support plate 15 by integrally connected graphite neck portion 20 which is in turn connected to rods 18 that extend up through opening 19 in plate 15 to support the anodes 21. Insulation 19' may be provided within hole opening 19 to provide insulation between the rod 18 and plate 15. An insulation shield 22 is provided above portions 20 of anode 21 to shield the anode 21 from collecting debris.

The graphite anode cell 14 rests upon threaded standards 23 provided with nuts 24 having openings 25 therein to adjust the same with a wrench upon the standard 23. An elongated support 26 is rigidly connected to the frame structure by bolts 29 which supports the standards 23. A skirt 28 extends across the elongated support 26 and down right into the tank for a purpose to be hereinafter described.

Mounted within the tank structure 5 is a carriage 30 provided with a pair of spaced-apart support plates 31. Spacer rods 32 and 33 extend between the support plates 31. At the upper end of each of the support plates 31 is mounted a roller 34 which is tracked on top of plate 13 on the U-shaped member 11. The rollers 34 are adapted to roll on plate 13 as hereafter described. A motor mount 35 is supported by spacer rods 32 and 33 by extending the motor mount 35 through openings 36 within the mount 35. Adjustable threaded rod 37 extends through a thread opening in the motor mount 35 for a purpose to be hereinafter described. Also, the outer portions of the threaded means 37 are provided with a mechanism to facilitate the entry of crank to move the motor mount laterally within the carriage.

Mounted on the supporting structure 35 is a motor 38 having a shaft 39 extending out one end thereof to which is mounted a cutterhead 40 provided with upstanding teeth 41.

The carriage 30 is moved longitudinally of the structure by a pair of spaced-apart endless chains 43 which are rigidly connected to the carriage 30 by a conventional connecting means 44. The chains 43 extend around sprockets 46 and 51 mounted on shafts 45 and 50. The shaft 45 is driven by motor 54 mounted on a support 55. The motor 54 is connected to a gear box 56 which in turn drives the sprocket 53. The sprocket 53 has a chain 48 extending therearound and drives another sprocket 47 mounted on the shaft 45.

At the opposite end of the resurfacing machine 1 is mounted a support stand 57 having a rotatable drum 59 mounted thereon. One portion of the drum provides a mounting for electrical lead 60 connected to the motor 38. The other portion of the drum provides a coil of hose 61 to provide water to wash the debris from the top of the cutterhead 40. The hose 61 is connected to a nozzle 62 which is mounted by support arm 63 to the motor.

In operation, the anode 14 is first removed from the chlorine manufacturing operation and is supported by the resurfacing machine 1 by the standards 23, extending through openings 16 in plate 15. It should be noted that the anode 14 is not rigidly connected to the machine but rests on the members 24 by its own Weight. In this manner, any force tending to push the anode cell upwardly will allow the anode 14 to float while being retained upon the standards 23 by its own weight.

Thereafter, the lateral position of the motor 38 with its cutterhead 40 attached thereto is moved to one side or the other by the adjusting mechanism 37. This is brought about by simply rotating the member 37 at its outer ends which will move the motor mount 35 thereon. Then, the motor 54 is actuated which rotates the shaft 45. The rotation of the shaft 45 drives the chains 43 and moves the carriage 30 through its connection at 44 therewith. Simultaneously with actuation of the motor 54, the motor 38 is actuated so as to rotate the cutterhead 40 to resurface the bottom portion of the anodes 21.

While the cutter mechanism 40 is being rotated, water is pumped through the hose 61 and ejected through the nozzles 62 which washes the debris away from the cutter teeth 41. Also, the drum 59 is rotated at the same speed as the chains 43 so that the hose 61 and leadline 60 will not drag and foul up the operation.

When the carriage 30 has reached the end of its stroke, the lateral moving means 37 is rotated to move the motor 38 laterally of the anodes 21. The amount of movement will be the width of the cutterhead 40. Then the motor mechanism 54 is reversed and the chains 43 move the carriage longitudinally of the resurfacing machine 1 in a reverse direction. The above cycle is repeated until the whole lower surface of the anode 14 is completely smoothed off.

Thereafter, the anode 14 is replaced into the chlorine manufacturing operation.

As is well known, graphite is a very brittle material since it consists of compressed carbon particles. Accordingly, care must be taken to prevent the anodes 21 from shattering as the cutterhead 40 smooths off its lower surface. Accordingly, if any upwardly directed force is created by the moving motor 38 and cutterhead 40, the vibrations caused by such cutting or resurfacing will be compensated for since the anode 14 is allowed to float on the standards 23. If the anode 14 were to be rigidly attached to the standards 23, the anodes 21 would crumble and break during the milling operation.

While specific details of a specific embodiment have been set forth above, it will be apparent that many changes and modifications may be made therein without departing from the spirit of the invention. It will, therefore, be understood that what has been described here is intended to be illustrative only, and is not intended to limit the scope of the invention.

What is claimed is:

1. A method of increasing the operating efficiency of a chlorine production cell wherein an electric current is passed through a brine solution maintained between a generally planar cathode and a set of consumable anodes which are suspended above and adjustably spaced as a unit from said cathode by means of a supporting frame structure, comprising the steps of:

(a) periodically removing said set of anodes as a unit from said cell by lifting said frame up and away from said cathode, without removing the individual anode elements from said supporting frame;

(b) lowering said frame into supporting position in a resurfacing machine so that said frame is supported by standards in said resurfacing machine in substantially the same position that said frame assumed in said cell;

(c) removing the erosion-caused irregularities in said anodes by cutting the lower surface of said anodes by a cutter means which moves within said resurfacing machine in a path which establishes a cutting plane in the lower surface of said anodes;

(d) repositioning said set of resurfaced anodes into said cell by transporting said frame from said resurfacing machine to said cell; and

(e) adjusting said frame so that the plane of said refinished anode surfaces is parallel to, but spaced from, said cathode.

2. The method of claim 1 including:

injecting water between the underside of said anodes and said cutting means to remove dislodged debris.

3. The method of claim 1 wherein:

said anodes are composed of graphite.

References Cited UNITED STATES PATENTS JOHN H. MACK, Primary Examiner.

S. S. KANTER, Assistant Examiner.

US. Cl. X.R. 15; 204-99 

